A rapidly evolving field of study suggests a link between the gut microbiome with obesity and type 2 diabetes. Recent studies show that environmental exposures, such as near-roadway and ambient air pollution (AAP) exposure can affect gut barrier integrity and modify risk for obesity and type 2 diabetes. In this study, Dr. Tanya Alderete proposes to examine the impacts of air pollution exposure on risk for obesity and insulin resistance via the gut microbiome and metagenome. In the K99 mentored phase, Dr. Alderete will build upon existing microbial, health, and exposure data from the ongoing longitudinal Children?s Health Study (CHS), which is examining the metabolic health impacts of air pollution exposure in Southern California. She will explore relationships between near-roadway and AAP with gut microbial community structure using 16S rRNA sequencing in 200 adolescents. Dr. Alderete will also analyze more complex microbial data from untargeted metagenomics to examine microbial genes, biochemical pathways, and markers of bacterial translocation associated with air pollution exposure in a subset of participants. She will advance her knowledge of environmental epidemiology and statistical analysis techniques used to analyze exposure and microbial data through didactic instruction, seminars, conferences, extensive hands-on training, and guidance from a diverse advisory committee of respected researchers. This multifaceted training plan will complement her expertise in clinical obesity and type 2 diabetes by providing her with new skills in: 1) environmental exposure assessment (e.g., near-roadway and AAP), 2) analysis techniques used in modern epidemiology and 3) statistical methods and study design used in microbiome research. In the R00 phase, she will initiate a new line of investigation by examining bacterial species, genes, and biochemical pathways related to obesity, insulin resistance, and gut barrier integrity in the full cohort of adolescents. By utilizing results and training from the K99 phase, she will uncover novel relationships between adiposity and insulin resistance with gut bacterial species and genes also related to air pollution exposure. Findings from these studies will improve our understanding of the mechanisms underlying relationships between increased air pollution exposure with obesity and type 2 diabetes risk. Characterization of the composition and function of the gut microbiome, in the context of air pollution exposure, has implications for prevention policy directed at reducing air pollution exposure. Results from this study also have the potential to identify novel biomarkers for disease and therapies targeting the gut microbiome. With this proposed study, Dr. Alderete is well positioned to take advantage of existing resources to develop independent, yet complementary projects, designed to help to fill critical gaps in our understanding of the the impacts of near-roadway and AAP exposure on the gut microbiome that may have far-reaching public health implications for obesity and metabolic disease.